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	$185.68	8.167%	$200.8445	$200.84	$200.85	$200.80
Purchase #2	$82.90	8.740%	$90.1455	$90.15	$90.15	$90.10
Purchase #3	$12.72	3.776%	$13.2003	$13.20	$13.20	$13.20
Purchase #4	$244.80	7.734%	$263.7328	$263.73	$263.75	$263.70
Purchase #5	$40.49	12.519%	$45.5589	$45.56	$45.55	$45.60
Purchase #6	$141.33	3.805%	$146.7076	$146.71	$146.70	$146.70
Purchase #7	$233.76	13.263%	$264.7636	$264.76	$264.75	$264.80
7 purchase totals =	$941.68		$1,024.9532	$1,024.95	$1,024.95	$1,024.90