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	$94.84	11.724%	$105.959	$105.96	$105.95	$106.00
Purchase #2	$53.28	4.280%	$55.5604	$55.56	$55.55	$55.60
Purchase #3	$128.69	12.424%	$144.6784	$144.68	$144.70	$144.70
Purchase #4	$133.85	7.650%	$144.0895	$144.09	$144.10	$144.10
Purchase #5	$228.62	6.485%	$243.446	$243.45	$243.45	$243.40
Purchase #6	$149.77	8.356%	$162.2848	$162.28	$162.30	$162.30
Purchase #7	$196.41	7.566%	$211.2704	$211.27	$211.25	$211.30
7 purchase totals =	$985.46		$1,067.2885	$1,067.29	$1,067.30	$1,067.40