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	$83.62	10.739%	$92.6	$92.60	$92.60	$92.60
Purchase #2	$185.98	9.367%	$203.4007	$203.40	$203.40	$203.40
Purchase #3	$30.46	9.657%	$33.4015	$33.40	$33.40	$33.40
Purchase #4	$236.84	7.331%	$254.2027	$254.20	$254.20	$254.20
Purchase #5	$167.88	11.315%	$186.8756	$186.88	$186.90	$186.90
Purchase #6	$176.72	11.228%	$196.5621	$196.56	$196.55	$196.60
Purchase #7	$173.52	6.830%	$185.3714	$185.37	$185.35	$185.40
7 purchase totals =	$1,055.02		$1,152.4140	$1,152.41	$1,152.40	$1,152.50