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	$111.32	5.148%	$117.0508	$117.05	$117.05	$117.10
Purchase #2	$179.69	3.360%	$185.7276	$185.73	$185.75	$185.70
Purchase #3	$15.91	3.518%	$16.4697	$16.47	$16.45	$16.50
Purchase #4	$40.72	7.826%	$43.9067	$43.91	$43.90	$43.90
Purchase #5	$120.44	3.743%	$124.9481	$124.95	$124.95	$124.90
Purchase #6	$232.30	13.816%	$264.3946	$264.39	$264.40	$264.40
Purchase #7	$175.68	11.602%	$196.0624	$196.06	$196.05	$196.10
7 purchase totals =	$876.06		$948.5599	$948.56	$948.55	$948.60