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	$174.69	3.332%	$180.5107	$180.51	$180.50	$180.50
Purchase #2	$85.65	6.110%	$90.8832	$90.88	$90.90	$90.90
Purchase #3	$93.32	3.488%	$96.575	$96.58	$96.60	$96.60
Purchase #4	$110.53	12.308%	$124.134	$124.13	$124.15	$124.10
Purchase #5	$191.25	11.731%	$213.6855	$213.69	$213.70	$213.70
Purchase #6	$219.33	11.181%	$243.8533	$243.85	$243.85	$243.90
Purchase #7	$98.69	13.342%	$111.8572	$111.86	$111.85	$111.90
7 purchase totals =	$973.46		$1,061.4989	$1,061.50	$1,061.55	$1,061.60