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	$119.69	4.397%	$124.9528	$124.95	$124.95	$125.00
Purchase #2	$131.50	7.550%	$141.4283	$141.43	$141.45	$141.40
Purchase #3	$152.78	9.218%	$166.8633	$166.86	$166.85	$166.90
Purchase #4	$245.48	9.296%	$268.2998	$268.30	$268.30	$268.30
Purchase #5	$125.72	3.437%	$130.041	$130.04	$130.05	$130.00
Purchase #6	$128.64	9.701%	$141.1194	$141.12	$141.10	$141.10
Purchase #7	$63.74	12.673%	$71.8178	$71.82	$71.80	$71.80
7 purchase totals =	$967.55		$1,044.5224	$1,044.52	$1,044.50	$1,044.50