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	$97.61	8.315%	$105.7263	$105.73	$105.75	$105.70
Purchase #2	$211.68	8.431%	$229.5267	$229.53	$229.55	$229.50
Purchase #3	$169.70	4.155%	$176.751	$176.75	$176.75	$176.80
Purchase #4	$109.88	4.868%	$115.229	$115.23	$115.25	$115.20
Purchase #5	$39.57	7.234%	$42.4325	$42.43	$42.45	$42.40
Purchase #6	$155.31	4.458%	$162.2337	$162.23	$162.25	$162.20
Purchase #7	$174.97	12.263%	$196.4266	$196.43	$196.45	$196.40
7 purchase totals =	$958.72		$1,028.3258	$1,028.33	$1,028.45	$1,028.20