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	$44.30	4.667%	$46.3675	$46.37	$46.35	$46.40
Purchase #2	$205.82	4.608%	$215.3042	$215.30	$215.30	$215.30
Purchase #3	$158.77	8.441%	$172.1718	$172.17	$172.15	$172.20
Purchase #4	$159.96	9.586%	$175.2938	$175.29	$175.30	$175.30
Purchase #5	$34.32	9.786%	$37.6786	$37.68	$37.70	$37.70
Purchase #6	$165.86	4.249%	$172.9074	$172.91	$172.90	$172.90
Purchase #7	$241.98	3.662%	$250.8413	$250.84	$250.85	$250.80
7 purchase totals =	$1,011.01		$1,070.5646	$1,070.56	$1,070.55	$1,070.60