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	$176.44	11.601%	$196.9088	$196.91	$196.90	$196.90
Purchase #2	$86.65	5.196%	$91.1523	$91.15	$91.15	$91.20
Purchase #3	$249.26	5.683%	$263.4254	$263.43	$263.45	$263.40
Purchase #4	$73.76	13.553%	$83.7567	$83.76	$83.75	$83.80
Purchase #5	$132.88	7.830%	$143.2845	$143.28	$143.30	$143.30
Purchase #6	$103.88	7.759%	$111.94	$111.94	$111.95	$111.90
Purchase #7	$235.48	3.571%	$243.889	$243.89	$243.90	$243.90
7 purchase totals =	$1,058.35		$1,134.3567	$1,134.36	$1,134.40	$1,134.40