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	$194.70	7.693%	$209.6783	$209.68	$209.70	$209.70
Purchase #2	$35.87	7.150%	$38.4347	$38.43	$38.45	$38.40
Purchase #3	$78.97	9.777%	$86.6909	$86.69	$86.70	$86.70
Purchase #4	$19.48	13.608%	$22.1308	$22.13	$22.15	$22.10
Purchase #5	$175.72	11.712%	$196.3003	$196.30	$196.30	$196.30
Purchase #6	$245.56	9.292%	$268.3774	$268.38	$268.40	$268.40
Purchase #7	$179.31	6.510%	$190.9831	$190.98	$191.00	$191.00
7 purchase totals =	$929.61		$1,012.5955	$1,012.59	$1,012.70	$1,012.60