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	$70.26	5.688%	$74.2564	$74.26	$74.25	$74.30
Purchase #2	$181.34	8.194%	$196.199	$196.20	$196.20	$196.20
Purchase #3	$168.55	11.507%	$187.945	$187.95	$187.95	$187.90
Purchase #4	$109.46	9.473%	$119.8291	$119.83	$119.85	$119.80
Purchase #5	$231.82	3.639%	$240.2559	$240.26	$240.25	$240.30
Purchase #6	$53.73	7.748%	$57.893	$57.89	$57.90	$57.90
Purchase #7	$236.72	4.447%	$247.2469	$247.25	$247.25	$247.20
7 purchase totals =	$1,051.88		$1,123.6253	$1,123.64	$1,123.65	$1,123.60