Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$175.68	11.572%	$196.0097	$196.01	$196.00	$196.00
Purchase #2	$168.28	11.736%	$188.0293	$188.03	$188.05	$188.00
Purchase #3	$112.70	10.783%	$124.8524	$124.85	$124.85	$124.90
Purchase #4	$155.50	7.557%	$167.2511	$167.25	$167.25	$167.30
Purchase #5	$234.97	8.419%	$254.7521	$254.75	$254.75	$254.80
Purchase #6	$118.86	6.860%	$127.0138	$127.01	$127.00	$127.00
Purchase #7	$195.53	8.124%	$211.4149	$211.41	$211.40	$211.40
7 purchase totals =	$1,161.52		$1,269.3233	$1,269.31	$1,269.30	$1,269.40