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	$163.86	4.576%	$171.3582	$171.36	$171.35	$171.40
Purchase #2	$104.69	4.614%	$109.5204	$109.52	$109.50	$109.50
Purchase #3	$169.29	5.548%	$178.6822	$178.68	$178.70	$178.70
Purchase #4	$126.34	4.141%	$131.5717	$131.57	$131.55	$131.60
Purchase #5	$216.63	5.537%	$228.6248	$228.62	$228.60	$228.60
Purchase #6	$146.38	4.824%	$153.4414	$153.44	$153.45	$153.40
Purchase #7	$76.72	4.824%	$80.421	$80.42	$80.40	$80.40
7 purchase totals =	$1,003.91		$1,053.6197	$1,053.61	$1,053.55	$1,053.60