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	$57.93	8.664%	$62.9491	$62.95	$62.95	$62.90
Purchase #2	$42.46	4.498%	$44.3699	$44.37	$44.35	$44.40
Purchase #3	$239.43	11.740%	$267.5391	$267.54	$267.55	$267.50
Purchase #4	$226.82	13.133%	$256.6083	$256.61	$256.60	$256.60
Purchase #5	$242.42	5.574%	$255.9325	$255.93	$255.95	$255.90
Purchase #6	$160.73	6.841%	$171.7255	$171.73	$171.75	$171.70
Purchase #7	$23.44	7.505%	$25.1992	$25.20	$25.20	$25.20
7 purchase totals =	$993.23		$1,084.3236	$1,084.33	$1,084.35	$1,084.20