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	$173.53	13.397%	$196.7778	$196.78	$196.80	$196.80
Purchase #2	$74.27	6.669%	$79.2231	$79.22	$79.20	$79.20
Purchase #3	$63.97	11.224%	$71.15	$71.15	$71.15	$71.20
Purchase #4	$134.63	7.397%	$144.5886	$144.59	$144.60	$144.60
Purchase #5	$50.50	9.501%	$55.298	$55.30	$55.30	$55.30
Purchase #6	$239.25	11.129%	$265.8761	$265.88	$265.90	$265.90
Purchase #7	$191.44	4.819%	$200.6655	$200.67	$200.65	$200.70
7 purchase totals =	$927.59		$1,013.5791	$1,013.59	$1,013.60	$1,013.70