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	$174.75	13.206%	$197.8275	$197.83	$197.85	$197.80
Purchase #2	$104.65	6.310%	$111.2534	$111.25	$111.25	$111.30
Purchase #3	$228.43	11.358%	$254.3751	$254.38	$254.40	$254.40
Purchase #4	$107.89	8.104%	$116.6334	$116.63	$116.65	$116.60
Purchase #5	$194.32	7.214%	$208.3382	$208.34	$208.35	$208.30
Purchase #6	$131.55	11.637%	$146.8585	$146.86	$146.85	$146.90
Purchase #7	$80.30	8.123%	$86.8228	$86.82	$86.80	$86.80
7 purchase totals =	$1,021.89		$1,122.1089	$1,122.11	$1,122.15	$1,122.10