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	$216.93	7.566%	$233.3429	$233.34	$233.35	$233.30
Purchase #2	$75.37	3.102%	$77.708	$77.71	$77.70	$77.70
Purchase #3	$238.98	3.713%	$247.8533	$247.85	$247.85	$247.90
Purchase #4	$19.32	4.690%	$20.2261	$20.23	$20.25	$20.20
Purchase #5	$96.73	11.795%	$108.1393	$108.14	$108.15	$108.10
Purchase #6	$146.29	3.301%	$151.119	$151.12	$151.10	$151.10
Purchase #7	$148.82	10.702%	$164.7467	$164.75	$164.75	$164.70
7 purchase totals =	$942.44		$1,003.1353	$1,003.14	$1,003.15	$1,003.00