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	$89.93	3.260%	$92.8617	$92.86	$92.85	$92.90
Purchase #2	$166.32	4.596%	$173.9641	$173.96	$173.95	$174.00
Purchase #3	$35.65	13.753%	$40.5529	$40.55	$40.55	$40.60
Purchase #4	$234.84	6.106%	$249.1793	$249.18	$249.20	$249.20
Purchase #5	$229.69	10.265%	$253.2677	$253.27	$253.25	$253.30
Purchase #6	$141.31	5.133%	$148.5634	$148.56	$148.55	$148.60
Purchase #7	$70.57	11.560%	$78.7279	$78.73	$78.75	$78.70
7 purchase totals =	$968.31		$1,037.1170	$1,037.11	$1,037.10	$1,037.30